The police absolutely work for us. We pay their paychecks, either through traffic tickets or taxes (hopefully more the latter than the former, but I don't know, some days it seems like they're out to get you). If they don't work for us, we ought to fire them.
"But in seriousness, unless some new evidence comes to light, the officer in this case probably won't be charged."
If it's determined that his injuries were solely because of a car crash (how could that have happened in this case?), then it is absolutely negligence. However, he died in custody, so it's almost irrelevant. I don't understand how a suspect can die in custody without receiving medical attention of any kind. How can you miss a severed spine? If your plumber comes to your home, "fixes" your sink, leaves, and then two days later, your house floods, you're gonna suspect him of fucking something up, right? So please forgive me if I suspect the police are in the wrong when someone dies in such a way when they just happen to be in custody. It's too convenient. Unless they, like Tolstoy said, mishandle evidence, which they are known to do, there will be new evidence or a confirmation of old evidence, but both lead to the same conclusion.